Hi, while I don't really post on this board, I follow more of an attachment parenting way (I guess).... in any case...
My son is almost 20 months old, still breastfed, co-sleeps and I have yet to see him sleep through a night (still waiting for that "it'll get better" to kick in :-p).
I don't think you're setting him for a bad sleeping habit, although this is my first and no one in my family (or that I know personally) has ever done anything like this... so I'm not entirely sure how this will turn out. But I've had ladies on my birth board (april 06) that have done this exact thing and their older children sleep fine by themselves now.
As for the bottle... one thing I HAD to stop doing with my son was I would constantly just nurse him whenever he woke up. He's my first and I knew no better and it was easy to get him to fall back asleep this way. Unfortunately, that DID set up a bad habit that I'm working on fixing now. I don't even produce as much milk anymore so I know that he's just using the breast to pacify. In any case, I stopped letting him nurse whenever he woke up, I'll pat his butt, whatever, to get him to fall back asleep without nursing.
It's not solved the problem, but it's helped. Have you tried to just cuddle him back without giving the bottle? Or what about keeping a cup of water by the bed so if he's thirsty he can just have a quick drink (and who knows, if you break that bottle in the night habit, that might solve the issue altogether).